Effects of different levels of probiotics on growth performance,antioxidant capacity and economic benefits of grass carp
To study the effects of different levels of probiotics on growth performance,antioxidant capacity and economic benefits of grass carp.840 healthy and disease-free grass carp with similar initial weight(426.68±1.35g)were selected for the experiment and randomly divided into 4 groups,with 3 replicates in each group,and 70 fish in each replicate.Each replicate was raised in independent net cages.The control group was given basic feed according to GB/T 36205-2018 Grass Carp Formula Feed,while the other three groups were added 1 g/kg,2 g/kg,and 3 g/kg probiotic additives to the basic feed,which were thoroughly stirred and fed.The experiment lasted for 90 days.The results showed that:(1)compared with the control group,the 2 g/kg probiotic group increased the final weight of grass carp by 8.20%(P＜0.05),the weight gain rate by 16.48%(P＜0.05),the specific growth rate by 11.54%(P＜0.05),and the feed coefficient by 13.07%(P＜0.05);The weight gain rate of grass carp in the 3 g/kg probiotic group increased by 13.00%(P＜0.05),and the feed coefficient decreased by 10.80%(P＜0.05).(2)Compared with the control group,the total antioxidant capacity of grass carp serum in the 1 g/kg probiotic group was significantly increased(P＜0.05),and the content of malondialdehyde was significantly reduced(P＜0.05);The total antioxidant capacity and superoxide dismutase activity of grass carp serum in the 2 g/kg probiotic group were significantly increased(P＜0.05),while the content of malondialdehyde was significantly reduced(P＜0.05);The total antioxidant capacity,superoxide dismutase and glutathione peroxidase activities of grass carp serum in the 3 g/kg probiotic group were significantly increased(P＜0.05),while the content of malondialdehyde was significantly reduced(P＜0.05).(3)As the level of probiotic addition increases,the weight gain and benefits of the four groups of grass carp first increase and then decrease,while feed costs continue to rise.After calculation,the final economic benefits were 2.09 yuan/tail,2.60 yuan/tail,3.13 yuan/tail,and 2.90 yuan/tail,respectively.The 2 g/kg probiotic group had the highest economic benefits.Conclusion:Different levels of probiotics can improve the growth performance,antioxidant capacity and economic benefits of grass carp.Overall,the appropriate level of probiotics addition is 2 g/kg.
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